Adaptive Immunity Flashcards
Methods for Adaptive Immune System
Cell Mediated Immunity
- T-cells
- Attack own Cells to remove tumors or other infections
T-Cell Lymphocyte Types
- Cytotoxic - Atks
- Helper - assists immune response by activating macrophages and B-cells with cytokines
- Regulatory - Prevents Immune Responce
Methods for Adaptive Immune System
Humoral Immunity
- Against outside forces
- Uses B lymph → Antibodies
Receptors
TCR
- T-Cell Receptors
- Require MHC molecule / presentation of molecule
- Have CD marker to identify antigen
Receptors
what is CD and what are the types?
- cluster of differentiation
- CD4 = Helper: HIV Binding Site
- CD8 = cytotoxic
Receptors
BCR
- B-cell Receptors
- Shaped like antibody that is fixed
- Binds to free-floating antigens
Costimulatory molecules
- Created by dendritic cells if microbial component discovered
- Attaches to surface of dendritic cell
- Helps with proliferation of T-cells
B cell types
- Plasma Cells: effectors which produce antibodies
- Memory: Keeps a little antigen and produces antibodies at low level in secondary lymphatic organ
Antibodies
What do Antibodies do?
- Complement System Activation
- Neutralization
- Opsonization
- Immobilzation and no adherence
- Cross linking: connecting similar bacteria so they can more easily be consumed by macrophages
- Antibody Dependent Cellular Cytotoxicity(ADCC)
Antibodies
What is Antibody Dependent Cellular Cytotoxicity(ADCC)?
- Surrounds cell in antibodies
- Allows for NK cells to send in perforin and protease containing granules by NK attaching to Fc region
How to Increase # of T/B cells
Clonal Selection Theory
Clonal Selection Theory
- If antigen perfectly matches to antibody, that lymphocyte will duplicate and create clones with exact same antibody
Immune Responces
Primary
- Requires most amount of time as there is no natural immunity
- Can allow fatal/ life threatening symptoms to emerge
- high number of IgM in this Response
Immune Responses
2ndary
- already have some basis for immunity
- can fight of infection earlier and maybe without symptoms
Types of Lymphocytes
- Naive: Have surface receptors but have not been activated
- Activated: Have been activated by an antigen or another cell which allows it to proliferate
- Effector: Attacks threat; doesn’t live long
- Memory: Reactivates when needed; lives long
Lymphatic System with Immune Resp.
- Moves T/ B cells around body to match 1 epitope
- Goes to lymphatic vessels and lymphatic organs
Epitope
Specific part of antigen recognized by antibody
Lymphatic system
Lymphatic Vessel
- Takes excess tissue fluid(lymph) and shuttles it around with antigens
- if tissue is inflammed, it will send more fluid into vessles
Lymphatic System
Primary Organs
- Bone Marrow: Produces B lymphocytes
- Thymus: Matures T lymph
- Go to secondary after fully maturated
Lymphatic System
Secondary Organs
- Nodes: Tissue cytokine transfer
- Spleen: Blood cytokine transfer
- Tonsils
In these sites: Antigens meet Antibodies
Lymphatic System
Where do Antigens meet Antibodies?
- Peyer’s Patches brought by dendritic cells and macrophages
- Leads to MALT
What is MALT?
Mucose Associated Lymphatic Tissue
Antigens
Immunogenic
How much can they do/ how much of a response can they trigger
Antigen
Types
- T- Dependent:
- Most antigens
- B-lymph require Th cell to activate
- T- Independent:
- B-lymph _do not_ require Th cell to activate
- Examples: LPS and polysacc in general[want to have identical and repeating subunits]
Cell-Mediated Immunity
Antigen Presentation
how antigens are presented to TCR by MHC with short peptide fragments
CMI
Parts of TCR
- Top 2 are variable while bottom are constant
- Left chain is alpha/ gamma(rarer)
- Right is Beta/ delta(rarer)
- connected by disulfide bond
CMI
Cross presentation
- Usually Dendrites
- Shows both Classes of MHC
CMI
Requirements for T cell to proliferate
- Dendrite
- MHC
CMI
Doesn’t have both prolif requirements?
- Apoptosis
OR - Becomes Treg
CMI
Antigen Presenting Cells
- Show to/through MHC Class II molecules
- expowered by Th CD4
Examples:
1. macrophages
2. dendritic cells
3. B-cells
CMI
Types of Th
- Th 1 = Macrophages and Tc
- Th 2 = Multicellular = Eosinophils and Basophils
- Th 17: Neutrophils
- Tfh = Humoral
CMI
What’s special about Tfh?
- Impaced by Leprosy / Hansen’s
- Tailored by MAMPS
CMI
T-cell MHCs
- Th = MHC class II(exogenous) <– antigen presenting cells
- Tc = MHC class I(endogenous) <– recognize non-native pepetides
CMI
What does Tc do when it recognizes non-native peptides?
- apoptosis of the host cell
- How:
- Perforin
CMI
How does Th activate macrophages?
- Through cytokines which are sent because:
- macrophage recognized non-native peptides
- What happens?
- Increased metabolism
- Increased amount of lysosomes
Humoral - Antibodies
IgM
- 5-13%
- 10 days
- in primary responce
- activate t-independent antigens
- Pentameters
- deal with blood infections
- work in classical pathway
Humoral - Antibodies
IgG
- 80-85%
- 21 days - longest lasting
- in secondary response
- does all killing:
- can cross placenta and is in colostrum
Humoral - Antibodies
IgA
- 10-13%
- 6 days
- Most in saliva: Works with mucosal immunity
- salivary (sIgA) IgA works in breast milk to provide immunity
Humoral - Antibodies
IgD
- < 1%
- 3 days
- Activation and Development of Immune Response
Humoral - Antibodies
IgE
- 0.01%
- 2 days
- Attaches to basophils and mast cells by Fc to let them release their granules in response to parasites
- May play a part in allergic rxns
Humoral - Antibodies
Colostrum
- first breast milk
Humoral
Germinal Center
- in secondary organs
- Direct B cells for response alongside Th cells
- take in proliferating B cells
Humoral
What is Affinity Maturation
- A rough? natural selection of BCR mutations
- the better the binding with antigens, the more it is favored
Humoral
What is Class Switching
- Switching which class of Ig produced
- Usually IgM produced
- Can be switched to IgG in lymph nodes
- OR IgA in MALT
Humoral
What do Memory cells do?
- Promote the activities of Germinal Centers
- Release cytokines
- have a slow and steady supply of antibodies after infection is over
- direct secondary immune responce
Humoral
Why is secondary response faster?
- use CMI and humoral
- Faster and more efficient
- uses less antigens to activate and proliferate b cells
Humoral-secondary
How do memory cells play a role?
- immediately go to memory cells
- promote A.M. and C.S.
- need to perfect less because memory cell already very close to the infection which leads to high amounts of IgG beinh produced to fight infection
Lymphocyte Development
Selection of Self Reactive lymphocytes: Negative
- B-cells: eliminate ‘self’ binders which are most, then they are dead
- T-cells: if they have self peptide recognition on their MHC, then they are dead = 95%
Lymphocyte Development
Selection of Self Reactive lymphocytes: Positive
- If a T cell has MHC, then they live!
Lymphocyte Development
Problem
- Too many unique epitopes to have with only 25,000 genes
Lymphocyte Development
Gene Arrangement
- Join various segments together
- Variety = 40
- Diversity =25
- Joining = 6
- Makes up both heavy and light chain variability –> 2x the variety and even more combinations!!!!!
Humoral
How does T-independent Response work?
- A polysaccaride(such as LPS) is recognized by BCR due to its identical repeating subunits leading to identical epitopes
- there is simultaneous BCR attachments and activation
Humoral
Hapten
- Binds to BCR
- Responds with large carrier compound
Humoral
Conjugate vaccine
- Uses a protein to covert a Independent antigen to a dependent antigen
Humoral
NK cells
- Use ADCC
- attach via Fc of IgG antibodies and release perforin and protease containing granules
- do some regulation with cytkines
- kill MCH class I cells that are stressed
